Crystal structure of NRAS Q61K with a ligand-induced pocket near switch II

Area of Science:

• Molecular Biology
• Structural Biology
• Oncology

Background:

• RAS proteins (KRAS, HRAS, NRAS) are key regulators of cell signaling, and their mutations drive various cancers.
• NRAS mutations are prevalent in skin and hematological malignancies, yet less studied structurally compared to KRAS and HRAS.
• Despite decades of being considered undruggable, targeted RAS inhibitors are emerging, highlighting the need for isoform-specific strategies.

Purpose of the Study:

• To present the crystal structure of the NRAS Q61K mutant in its active, GTP-bound form.
• To identify potential novel binding sites for therapeutic intervention against NRAS mutations.
• To gain insights into the mechanism of impaired GTP hydrolysis in NRAS-Q61K.

Main Methods:

• X-ray crystallography was used to determine the structure of the NRAS Q61K mutant bound to GTP.
• Structural analysis focused on the active site and surrounding regions, particularly near switch II.
• Biochemical insights into GTP hydrolysis were derived from the resolved catalytic site.

Main Results:

• A novel, previously uncharacterized pocket was identified near the switch II region of NRAS Q61K upon ligand binding.
• The crystal structure provides a detailed view of the GTP-bound NRAS Q61K active site.
• The structure offers mechanistic explanations for the observed stalled GTP hydrolysis in NRAS-Q61K.

Conclusions:

• The identified pocket represents a potential druggable target for developing specific inhibitors against mutant NRAS.
• This structural information is crucial for designing next-generation NRAS-targeted cancer therapies.
• Further research into NRAS structural biology can unlock new therapeutic avenues for NRAS-mutated cancers.